Communication connection merge method and node to be used therefor

ABSTRACT

A communication connection merge method and a node to be employed in the same can merge parameter of LSP, such as request bandwidth or the like, upon performing merging. The communication connection merge method performs merge process for consolidating a plurality of communication connection of a connection-oriented network at a node on the way of transfer route into a common communication connection by making judgment of possibility to have a common transfer route from a node to merge to an egress node upon merging new communication connection on setting for existing communication connection, modifying collateral parameter of the existing communication connection which is judged to merge the new communication connection for enabling accommodation of the new communication connection in the existing communication connection, and performing merge after modification of parameter of the existing communication connection.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.09/727,046 filed Nov. 30, 2000 which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a communication connectionmerge method and anode to be employed therein. Particularly, theinvention relates to a communication connection merge method and node tobe employed therein, which merges a plurality of communicationconnection set in a connection-oriented network during communicationwith simultaneously updating collateral parameter on a common pathperforming merging.

2. Description of the Related Art

Conventionally, a communication connection merge method and a node to beemployed in the same is used for merging communication connections whichmake transfer path from a merge point to an egress label switchingrouter (LSR) common, upon setting a label switching path (LSP) in aMultiProtocol Label Switching (MPLS) network as disclosed in InternetDraft, draft-ietf-mpls-arch-06.txt, August, 1999 and Internet Draft,draft-ietf-mpls-ldp-06.txt, October, 1999, for example.

Here, merge means consolidating a plurality of transfer paths into asingle transfer path at a mid-way. In a path from a merge point to anegress LSR, the same transfer path identifier (here, a label of MPLS) isused for the packet. By performing merging, number of transfer label ofLSR can be reduced to contribute for operation of a large-scale network.

Next, the prior art will be discussed with assumption thatconnection-oriented network being MPLS network, communication connectionbeing LSP and node being LSR. Referring to FIG. 9, the MPLS network 1 isconstructed with LSRs 101 to 104. Respective LSR 101 to 104 areconnected through links 201 to 203. Data is exchanged through theselinks 201 to 203. On the other hand, an LSP 301 routed from the LSR 101to the LSR 103 via the LSR 102 is present.

Here, consideration is given for the case that new LSP is establishedfrom the LSR 104 to the LSR 103, at first, the LSR 104 feeds an LSPsetup request 401 for the LSR 103 to the LSR 102 using an LSP settingprotocol. The LSR 102 receiving the LSP setup request 401 makes judgmentwhether or not LSP to be merged to the LSR 103 is present. If present,merging is performed. Here, since the LSP 301 which makes the path to anegress router in common, is already present, merging can be performed.

Upon performing merging, setting of LSP is not requested beyond the LSR102 (namely to the LSR 103), an LSP setup response 402 is returned tothe LSR 104. Then, with taking the LSR 104 as starting point, an LSP 302to be merged to the LSP 301 is set in the LSR 102.

In the conventional communication connection merge method, collateralparameter (called parameter), such as request bandwidth or the likeowned by the LSP cannot be merged upon performing merging. This isbecause the merging is performed without modifying the parameter ofexisting LSP.

As an example of such parameter, there are parameter relating totraffic, such as request bandwidth, delay or the like, parameterrelating to policy, such as Virtual Private Network (VPN) identifier,preference or the like.

On the other hand, in the conventional communication connection mergemethod, once merging is performed, the merged LSP cannot be branched atthe mid-way. Therefore, even if the parameter, such as request bandwidthor the like owned by the LSP could be merged together, the range ofapplication is limited to the case where transfer path to the egress LSRcan be common. For example, even if the most portion of the transferpath is common, merging cannot be performed if the egress LSR isdifferent.

SUMMARY OF THE INVENTION

Therefore, the present invention has been worked out for solving theproblem. It is an object of the present invention to provide acommunication connection merge method and a node to be employed in thesame, which can merge parameter of LSP, such as request bandwidth or thelike, upon performing merging.

Another object of the present invention to provide a communicationconnection merge method and a node to be employed in the same, which canmerge the parameter of the LSP together and can branch the LSP oncemerged.

According to the first aspect of the present invention, a communicationconnection merge method performing merge process for consolidating aplurality of communication connection of a connection-oriented networkat a node on the way of transfer route into a common communicationconnection, comprises:

a step of making judgment of possibility to have a common transfer routefrom a node to merge to an egress node upon merging new communicationconnection on setting for existing communication connection;

a step of modifying collateral parameter of the existing communicationconnection which is judged to merge the new communication connection forenabling accommodation of the new communication connection in theexisting communication connection; and

a step of performing merge after modification of parameter of theexisting communication connection.

According to the second aspect of the present invention, a communicationconnection merge method performing merge process for consolidating aplurality of communication connection of a connection-oriented networkat a node on the way of transfer route into a common communicationconnection, comprises:

a step of making judgment whether a tunneling communication connectionis present in a section where the existing communication connection andthe new communication connection have a common transfer route uponmerging new communication connection on setting for exsitingcommunication connection;

a step of modifying collateral parameter of the tunneling communicationconnection to merge the new communication connection for enablingaccommodation of the new communication connection in the tunnelingcommunication connection; and

a step of performing merge the existing communication connection and thenew communication connection on the tunneling communication connectionin a condition to be branched at a terminal point node aftermodification of parameter of the existing communication connection.

According to the third aspect of the present invention, a communicationconnection merge method performing merge process for consolidating aplurality of communication connection of a connection-oriented networkat a node on the way of transfer route into a common communicationconnection, comprising:

a step of newly setting a tunneling communication connection capable ofaccommodating collateral parameter of the existing communicationconnection and the new communication connection in a section where theexisting communication connection and the new communication connectionhave a common transfer route upon merging new communication connectionon setting for existing communication connection; and

a step of performing merge the existing communication connection and thenew communication connection on the tunneling communication connectionin a condition to be branched at a terminal point node aftermodification of parameter of the existing communication connection.

According to the fourth aspect of the present invention, a nodeperforming merge process for consolidating a plurality of communicationconnection of a connection-oriented network at a node on the way oftransfer route into a common communication connection, comprises:

means for making judgment of possibility to have a common transfer routefrom a node to merge to an egress node upon merging new communicationconnection on setting for existing communication connection;

means for modifying collateral parameter of the existing communicationconnection which is judged to merge the new communication connection forenabling accommodation of the new communication connection in theexisting communication connection; and

means for performing merge after modification of parameter of theexisting communication connection.

According to the fifth aspect of the present invention, a nodeperforming merge process for consolidating a plurality of communicationconnection of a connection-oriented network at a node on the way oftransfer route into a common communication connection, comprises:

means for making judgment whether a tunneling communication connectionis present in a section where the existing communication connection andthe new communication have a common transfer route upon merging newcommunication connection on setting for existing communicationconnection;

means for modifying collateral parameter of the tunneling communicationconnection to merge the new communication connection for enablingaccommodation of the new communication connection in the tunnelingcommunication connection; and

means for performing merge the existing communication connection and thenew communication connection on the tunneling communication connectionin a condition to be branched at a terminal point node aftermodification of parameter of the existing communication connection.

According to the sixth aspect of the present invention, a nodeperforming merge process for consolidating a plurality of communicationconnection of a connection-oriented network at a node on the way oftransfer route into a common communication connection, comprises:

means for newly setting a tunneling communication connection capable ofaccommodating collateral parameter of the existing communicationconnection and the new communication connection in a section where theexisting communication connection and the new communication connectionhave a common transfer route upon merging new communication connectionon setting for existing communication connection; and

means for performing merge the existing communication connection and thenew communication connection on the tunneling communication connectionin a condition to be branched at a terminal point node aftermodification of parameter of the existing communication connection.

Namely, in the communication connection merge method according to thepresent invention, the label switching router upon receipt of the labelswitched path setup request makes judgment whether or not the newly setlabel switched path can be merged to the existing label switched path.As a criterion for judgment, in addition to have a common route to theegress label switching router, it is checked whether the parameter ofthe existing label switched path can be modified so that the parameterof the new label switched path having parameter, such as requestedbandwidth or the like may be accommodated in the existing label switchedpath.

For modifying parameter of the existing label switched path, negotiationhas to be performed for all of label switching routers on downstreamside of the label switching router to merge whether or not parameter canbe modified. This can be realized by signaling or the like. As a resultof negotiation, if modification of parameter is possible, merge isperformed.

On the other hand, if modification of the parameter is not possible,merge is not performed to send the label switched path setup request tothe downstream side label switching router for setting another labelswitched path. By employing such method, parameter, such as requestedbandwidth or the like can be merged together with the label switchedpath, upon merging.

Also, in the communication connection merge method according to thepresent invention, when the tunneling label switched path ispreliminarily set in the multi-protocol label switching network, as apart of the route of the label switched path to be newly established, iftunneling label switched path can be used, negotiation is performed formodifying parameter of the tunneling label switched path so that thenewly established label switched path may be accommodated in thetunneling label switched path in the process similar to those set forthabove. As a result of negotiation, if modification of parameter ispossible, the label switched path may be set with using the tunnelinglabel switched path as a part of the route of the label switched path.

In the portion where the tunneling label switched path is used as a partof transfer route of the label switched path, label stack of themulti-protocol label switching is employed for the transfer packet toadd the label of the tunneling label switched path in front of the labelof the label switched path. In the tunneling label switched path, aplurality of the label switched path can be accommodated. In the portionother than the tunneling label switched path, the routes of theaccommodated label switched paths are not necessarily the same.

By employing such method, it becomes possible to merge the parameter oflabel switched path together with the label switched path, and inconjunction therewith, the label switched path once merged can bebranched on the way.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detaileddescription given hereinafter and from the accompanying drawings of thepreferred embodiment of the present invention, which, however, shouldnot be taken to be limitative to the invention, but are for explanationand understanding only.

In the drawings:

FIG. 1 is an illustration for explaining the first embodiment of acommunication connection merge system according to the presentinvention;

FIG. 2 is a flowchart showing an operation in an LSR 102 in the firstembodiment of the communication connection merge system according to thepresent invention;

FIG. 3 is a flowchart showing an operation in an LSR 103 in the firstembodiment of the communication connection merge system according to thepresent invention;

FIG. 4 is an illustration for explaining the second embodiment of acommunication connection merge system according to the presentinvention;

FIG. 5 is an illustration for explaining the second embodiment of acommunication connection merge system according to the presentinvention;

FIG. 6 is an illustration for explaining a structure of a MPLS packet;

FIG. 7 is a flowchart showing an operation in an LSR 107 in the secondembodiment of the communication connection merge system according to thepresent invention;

FIG. 8 is an illustration for explaining the second embodiment of acommunication connection merge system according to the presentinvention; and

FIG. 9 is an illustration for explaining the conventional mergeoperation in the MPLS network.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will be discussed hereinafter in detail in termsof the preferred embodiment of the present invention with reference tothe accompanying drawings. In the following description, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. It will be obvious, however, tothose skilled in the art that the present invention may be practicedwithout these specific details. In other instance, well-known structuresare not shown in detail in order to avoid unnecessary obscurity of thepresent invention.

FIG. 1 is an illustration for explaining the first embodiment of acommunication connection merge system according to the presentinvention. In FIG. 1, the first embodiment of the present invention ispremised for application to a MPLS network 1 as a representative of aconnection-oriented network.

The MPLS network 1 is consisted of LSRs 101 to 104. Respective LSRs 101to 104 are connected to links 201 to 203. On the other hand, an LSP 301is set from the LSR 101 to the LSR 103 via the LSR 102.

FIG. 2 is a flowchart showing an operation in an LSR 102 in the firstembodiment of the communication connection merge system according to thepresent invention, and FIG. 3 is a flowchart showing an operation in anLSR 103 in the first embodiment of the communication connection mergesystem according to the present invention. The operation of the firstembodiment of the present invention will be discussed with reference toFIGS. 1 to 3.

At first, consideration will be given for the case where a new LSP isestablished from the LSR 104 to the LSR 103 via the LSR 102. Here, theLSP to be newly set has parameters, such as request bandwidth or thelike. The LSR 102 receives an LSP setup request 401 transmitted from theLSR 104 (step S1 of FIG. 2).

The LSR 162 receiving the LSP setup request 401 checks whether the LSPhaving a common route to the egress LSR 103 from the LSR 102 (step S2 ofFIG. 2). When such LSP is present, merging is not performed and theprocess is transit to a procedure for setting the LSP (step S12 of FIG.2).

As a result of judgment at step S2, if LSP, in which a route from theLSR 102 to the LSR 103 is common is present, a check is performedwhether the existing LSP has the same kind of parameter as that of theLSP to be newly established (step S3 of FIG. 2). If the existing routedoes not have the same kind of parameter as that of the LSP to be newlyestablished merge cannot be performed. Therefore, the process isadvanced to the LSP establishing procedure without performing merge(step S12 of FIG. 2).

As a result of judgment at step S3, it is assumed that the LSP 301having the same kind of parameter as the LSP to be newly set, ispresent. In this case, a check is performed in the LSR 102 whether ornot the parameter of the LSP 301 can be modified (step S4 of FIG. 2). Ifmodification of the parameter is not possible, the process is advancedto the LSP establishing procedure without performing merge (step S12 ofFIG. 2).

As a result of checking at step S4, if modification of the parameter ispossible, the modification is set temporarily (step S5 of FIG. 2). Here,temporarily set means obtaining of a resource for modification of theparameter without actually modifying the parameter of the LSP.Furthermore, a parameter modification request 403 of the LSP 301 istransmitted along the transfer route of the LSP 301. Then, a response tothe request is waited. (steps S6 and S7 of FIG. 2).

The LSR 103 upon receipt of the parameter modification request 403 ofthe LSP 301, checks whether or not modification of the parameter of theLSP 301 as requested is possible (steps S21 and S22 of FIG. 3). Ifmodification is not possible, rejection of modification of the parameteris noticed to the LSR which transmitted the request (upstream LSR: inthis case LSR 102) (step S30 of FIG. 3).

As a result of checking at step S22, if modification is possible,modification of the parameter is temporary (step S23 of FIG. 3). Here,if the own node is the egress LSR, the modification of the parameter isfixed as is (steps S24 and S27 of FIG. 3). In case of the LSR 103, sinceit is the egress LSR, this procedure is applied.

If the LSR is not the egress LSR, the parameter modification request istransmitted to the downstream LSR on the LSP to wait for the response(steps S24 to S26 of FIG. 3). When the rejection of modification ofparameter is noticed from downstream LSR, rejection of modification ofparameter is transmitted to the upstream LSR (step S29, S30 of FIG. 3).

On the other hand, if the parameter modification response is receivedfrom the downstream LSR, the modification of the parameter is fixed(step S27 of FIG. 3). After fixing the modification of parameter, theparameter modification response 404 is transmitted to the upstream LSR(step S28 of FIG. 3).

When the LSR 102 receives the rejection of parameter modification fromthe downstream LSR, temporary setting of the parameter modification isreleased to transit to the LSP setting procedure without performingmerge (steps S9 and S12 of FIG. 2).

When the LSR 102 receives the parameter modification response from thedownstream LSR, the parameter modification is fixed to perform merge ofthe LSP (step S8 and S10 of FIG. 2). Then, an LSP setting response 402is transmitted to the LSR 104 (step 511 of FIG. 2). As a result, settingof the LSP 302 to be merged to the LSP 301 by the LSR 102 with takingthe LSR 104 as merge point, is completed.

The shown embodiment is characterized by modification of the parameterof the existing LSP so that the parameter of the LSP to be newlyestablished may be accommodated in the existing LSP from the merge pointto the egress LSR in addition to the case where the route is taken ascommon in the path from the merge point to the egress LSR, upon mergingthe LSP to be newly established into the existing LSP. By this, itbecomes possible to merge the LSP with collateral parameter, such asrequested bandwidth or the like, for example.

On the other hand, in the shown embodiment, merge is taken place aftermodification of the parameter of the existing LSP in the section fromthe merge point to the egress LSR. However, when the LSP once merged isto be released, releasing may be taken place after modification of theparameter so that the LSP remained may be accommodated, is negotiated(step S13 in FIG. 2).

Furthermore, the present invention may be implemented in other ways withtaking Asynchronous Transfer Mode (ATM) network as a replacement of theMPLS network, a Virtual Channel (VC) as a replacement of the LSP, and anATM switch as a replacement of the LSR.

FIGS. 4 and 5 are illustration for explaining the second embodiment ofthe present invention. The second embodiment of the present inventionwill be discussed with reference to FIGS. 4 and 5. Here, the secondembodiment of the present invention is premised to perform merge underthe condition where the MPLS network is employed for performing mergingas a representative of the connected oriented network.

The MPLS network is constructed with the LSRs 105 to 111. RespectiveLSRs are connected by links 204 to 209. On the other hand, a tunnelinglink LSP 303 from the LSR 107 as starting point to the LSR 109 via theLSR 108. Furthermore, LSP 304 from the LSR 105 as starting point to theLSR 110 via the LSRs 107 and 109 are also set preliminarily.

Among the transfer route of the LSP 304, the tunneling LSP 303 is usedbetween the LSR 107 and the LSR 109. This portion is realized using anMPLS label stack. Between the LSR 107 and the LSR 109, a label assignedfor the tunneling LSP 303 is stacked in front of the label assigned forthe LSP 304.

FIG. 6 is an illustration for explaining a construction of the MPLSpacket. In FIG. 6, there is shown the structure of an MPLS packetflowing on the LSP 304 between the LSR 107 and the LSR 109.

An MPLS packet 501 has shim headers 504 and 505, which precede an IPheader 503. Each shim header includes an MPLS label. A label in the shimheader 504 is assigned for the LSP 304, and one in the shim header 505for the tunneling LSP 303.

Note that the shim header 505 is applied only between the LSR 107 andthe LSR 109 to be used as the transfer route in which the tunneling LSP303 is used as the transfer assignment. In the other sections, the shimheader 504 appears at the top stack entry.

FIG. 7 is a flowchart showing an operation of the LSR 107 in the secondembodiment of the present invention. The operation of the secondembodiment of the present invention will be discussed with reference toFIGS. 4, 5 and 7.

Let us consider the case that the LSP from the LSR 106 to the LSR 110via the LSR 107 is initiated. Here, the initiated LSP includescollateral parameters, such as requested bandwidth or the like.

The LSR 106 transmits the LSP setup request 405 to the LSR 107. The LSR107 upon receipt of the LSP setup request 405 checks whether the LSPhaving the common route to the egress LSR in the similar manner as thatin the first embodiment of the invention (step S41 and S42 in FIG. 7).If such LSP is present, attempt is made to merge the newly establishedLSP to the existing LSP having the common route to the egress LSR. InFIG. 4, the LSP 304 is the LSP to be merged.

At first, the LSP 304 checks whether the LSR 107 uses the tunneling LSPas a part of the transfer route (step S43 in FIG. 7). As a result ofchecking at step S43, if the LSP 304 uses the tunneling LSP as apart ofthe transfer route at the LSR 107, modification of the parameter of thetunneling LSP is negotiated in the similar manner as step S13 of FIG. 2so that the newly established LSP may be accommodated (step S45 in FIG.7). In FIG. 4, since the LSP 304 uses the tunneling LSP 303 as a part ofthe transfer route at the LSR 107, the process is moved from step S43 toS45.

Step S13 in FIG. 2 is the portion surrounded by the broken line, whichbecomes OK when modification of the parameter is successful, and becomesNG when modification of the parameter is failed in certain reason. IfOK, the process transits to step S10 in the case of FIG. 2 and to stepS12 otherwise.

At step S45, when modification of parameter is successful, exchange ofmessage relating to modification of parameter is performed insequentially order of transmitting the parameter modification request407 from the LSR 107 to the LSR 108, transmitting the parametermodification request 409 from the LSR 108 to the LSR 109, transmittingthe parameter modification response 410 from the LSR 109 to the LSR 108,and transmitting the parameter modification response 408 from the LSR108 to the LSR 107.

As a result of process at step S45, if the modification of parameter isnot successful, the procedure to establish the LSP is executed in placeof executing merge (step S52 in FIG. 7). If the modification ofparameter is successful, the parameter of LSP 304 itself is modified(step S47 in FIG. 7).

At step S47, when modification of parameter is successful, exchange ofmessage relating to modification of parameter is performed insequentially order of transmitting the parameter modification request411 from the LSR 107 to the LSR 109, transmitting the parametermodification request 413 from the LSR 109 to the LSR 110, transmittingthe parameter modification response 414 from the LSR 110 to the LSR 109,and transmitting the parameter modification response 412 from the LSR109 to the LSR 107.

As a result of checking at step S43, if the LSP 304 does not use thetunneling LSP as a part of the transfer route in the LSR 107, theprocess is transit to step S47 directly to perform modification ofparameter of the LSP 304 (step S47 in FIG. 7).

As a result of process at step S47, if the modification of parameter isnot successful, the process is moved to the procedure for setting theLSP without performing merge (step S52 in FIG. 7). If the modificationof parameter is successful, the LSP to be newly established is merged tothe LSP 304 to transmit the LSP setup response 406 to the LSR 106 stepsS50 and S51 in FIG. 7). As a result of the process at steps S50 and S51,setting of the LSP 305 from the LSR 106 as the starting point and mergedto the LSP 304 at the LSR 107 is completed.

Next, discussion will be given for the operation when the LSP having thecommon route to the egress LSR does not exist in the LSR 107 uponreceipt of the LSP setup request 405 at step S42. FIG. 5 shows the casewhere the LSR 106 initiates the setup request of the LSP to the LSR 111via the LSR 107.

At first, check is performed whether or not the route to the terminalend of the tunneling LSP set at the LSR 107 may be taken as a part ofthe route to the egress LSR (step S44 in FIG. 7). Here, the startingpoint of the tunneling LSP is not necessarily LSR 107.

As a result of checking at step S44, if the route up to the terminal endof the tunneling LSP 303 as set in the LSR 107 cannot be a part of theroute of the LSP to be newly established, attempt to make the newlyestablished LSP to be accommodated in the tunneling LSP and theprocedure to establish the LSP is executed (step S52 in FIG. 7).

As a result of checking at step S44, if the route up to the terminal endof the tunneling LSP 303 as set in the LSR 107 can be a part of theroute of the LSP to be newly established, which corresponds the caseillustrated in FIG. 5, for example, modification of parameter isperformed so that the LSP to be newly established can be accommodated(step S46 in FIG. 7).

At step S46, exchange of the message relating to modification ofparameter is similar to the same as the case where the modification ofparameter is successfully at step S45.

As a result of the step S46, if the modification of parameter is notsuccessful, attempt to accommodate the LSP to be newly established inthe tunneling LSP 303 and process is transit to the procedure forestablishing the LSP (step S52 in FIG. 7). If modification of parameteris successful, the newly established LSP is accommodated in thetunneling LSP 303 to transmit the LSP setup request to the LSR 109 asterminal end of the tunneling LSP 303 (steps S48 and S49 in FIG. 7).

Exchange of the message in the case that LSP setting is successful atstep S49 and subsequent steps is performed in the sequential order oftransmission of the LSP setup request 417 from the LSR 109 to the LSR111, transmission of the LSP setup response 418 from the LSP 111 to theLSP 109, transmission of the LSP setup response 416 from the LSR 109 tothe LSR 107, and transmission of the LSP setup response 406 from the LSR107 to the LSR 106.

If the setting of the LSP fails at step S49 and subsequent steps,accommodation to the tunneling LSP 303 is released at step S48 to makesetting of LSP error.

When the LSP setting is successful at step S49 and subsequent steps,setting of LSP 306 from the LSR 106 as being start point LSR 106 to theLSR 111 via the LSR 107 and the LSR 109 is completed. Among the transferroute of the LSP 306, in the section from the LSR 107 to the LSR 109,merge is performed on the LSP 304 and the tunneling LSP 303.

Next, discussion will given for the packet structure of the MPLStransferred on the LSP 306. Among the LSP 306, in the portion where thetunneling LSP 303 is used as the transfer route, the shim header storingthe label assigned for the LSP 303 is added in front of the shim headerstoring the label assigned for the LSP 306, is transferred.

For example, between the LSR 107 and the LSR 108, the shim headerstoring the label assigned for the LSP setup response 408 is added infront of the shim header storing the label assigned to the LSP setupresponse 416.

In the shown embodiment, when the tunneling LSP can be used as a part ofthe route of the newly established LSP, modification of the parameter ofthe tunneling LSP is negotiated so that the newly established LSP can beaccommodated in the tunneling LSP. If modification is possible, thetunneling LSP is used as a part of the LSP to be newly established.

In addition, it is already known that the tunneling LSP can accommodatethe newly established LSP without negotiation, negotiation is notperformed and the newly established LSP is accommodated in the tunnelingLSP. Namely, step S46 of FIG. 7 is omitted.

On the other hand, in the shown embodiment, discussion has been madeunder the premise that the tunneling LSP is preliminarily set. However,when the tunneling LSP is not present, the newly established LSP mayhave a part of the route common to existing route. At this time, in thecommon portion, the tunneling LSP is newly set. Then, in the newly settunneling portion, the newly established LSP may be merged to theexisting LSP.

Namely, in this case, at step S46 of FIG. 7, instead of negotiatingmodification of parameter of the tunneling LSP, the tunneling LSP is setso as to accommodate both of the newly established LSP and the existingLSP.

On the other hand, while two level of label stack is used in the shownembodiment, this can be extended to arbitrary number of levels. Namely,the present invention is applicable for the case where the tunneling LSPis used as a part of the route of another tunneling LSP to stackarbitrary number of stacks.

Furthermore, the present invention may be implemented in other way withtaking Asynchronous Transfer Mode (ATM) network as a replacement of theMPLS network, a Virtual Channel (VC) as a replacement of the LSP, and anATM switch as a replacement of the LSR. In this case, in the portiontunneled by the tunneling VP, VP switching is performed.

In the shown embodiment, since merge is performed only in the transferroute portion of the tunneling LSP, it becomes not only possible toperform merge of the LSP having collateral parameter, but also canperform branching at the portion other than the transfer route portionof the tunneling LSP.

In FIG. 5 of the shown embodiment, LSP 304 and the LSP 306 are mergedbetween the LSR 107 and the LSR 109 by the tunneling LSP 303, the LSR110 and the LSR 111 are branched at the LSR 109.

Next, the first embodiment of the present invention illustrated in FIG.1 will be discussed again in greater detail. In the shown embodiment,LSRs 101 to 104 are present in the MPLS network 1. Respective LSRs 101to 104 are connected to the links 201 to 203. On the other hand, the LSP301 taking the LSR 101 as starting point and the LSR 103 as terminalpoint is preliminarily established via the LSR 102. To the LSP 301, as areserved bandwidth for transit link, 10 Mbit/sec. is set in each of theLSRs 101 to 104.

Here, it is assumed that LSP is newly set from the LSR 104 to the LSR103 as the terminal point via the LSR 102. Here, it is assumed that abandwidth to be reserved for the LSP to be newly established is 5Mbit/sec.

The LSR 104 temporarily set the reversed bandwidth of 5 bit/sec. at ownnode and transmits the LSP setup request (label request message) 401 tothe LSR 102. In the LSP setup request 401, information indicative thatthe transit nodes are the LSR 102 and the LSR 103 and traffic parameterindicating that the bandwidth to be reserved is 5 bit/sec are contained.

The LSR 102 upon receipt of the LSP setup request 401 performs retrievalof the LSP that may have the route to the egress LSR 103 in common withthe newly established LSP, at the LSR 102. Here, the LSP 301 is found inthe retrieval, which LSP 301 has the common route up to the egress LSR103.

Next, check is performed whether the LSP 301 has the parameter of thereserved bandwidth. If the LSP 301 has the parameter of the reservedbandwidth, the parameter is modified to permit merge of the newlyestablished LSP.

Here, check is performed whether the reserved bandwidth of 10 Mbits/sec.of the LSP 301 may be combined with the bandwidth of 5 Mbits/sec. to bereserved for the newly established LSP. If the reserved bandwidth can becombined to modify to 15 Mbits/sec. in total, the reserved bandwidth ofthe LSP 301 is temporarily set at the modified value at the LSR 102.

Next, the LSR 102 transmits the parameter modification request 403 tothe LSR 103. In the parameter modification request 403, the value of 15Mbit/sec. as the reserved bandwidth of the LSP 301 to be modified iscontained.

The LSP 103 upon receipt of the parameter modification request makesjudgment whether or not the reserved bandwidth of the LSP 301 can bemodified to 15 Mbit/sec. If modification is possible, the reservedbandwidth of the LSP 301 is modified to 15 Mbit/sec. Then, parametermodification response 404 is returned to the LSR 102.

The LSR 102 upon receipt of the parameter modification response 404fixes the temporarily set parameter and returns LSP setup response(label mapping message) 402 to the LSR 104. In the LSP setup response402, a label value ton be used when the packet of the MPLS flowing onthe LSP 302 after setting is transferred from the LSR 104 to the LSR102. The label value is bound with the transfer label from the LSR 102to the LSR 103 in the LSP 301.

The LSR 104 upon receipt of the LSP setup response 402 fixes thetemporarily set bandwidth reservation, and merges the newly establishedLSP to the LSP 301 to terminate setting of the LSP. Namely, the LSP 302from the LSR 105 as the starting point to be merged to the LSP 301 atthe LSR 102 is set. The LSP 302 may have the reserved bandwidth 5bit/sec. and has the reserved bandwidth 15 Mbit/sec. from the LSR 102 tothe LSR 103.

FIG. 8 is an illustration for explaining the second embodiment of thepresent invention. Discussion will be given hereinafter for the secondembodiment of the present invention with reference to FIG. 8.

The MPLS network 1 is consisted of the LSRs 112 to 118. Respective LSRs112 to 118 are connected by the links 210 to 215. On the other hand, theMPLS network 1 is divided into regions of the areas 2, 3 and backbone 4of the Open Shortest Path First (OSPF) routing protocol.

It is assumed that the LSP 308 from the LSR 113 as starting point to theLSR 117 as terminal point via the LSR 114 and the LSR 116 ispreliminarily established. A section between the LSR 114 and the LSR 116where the LSP 308 passes through the backbone 4, is tunneled by thetunneling LSP 307 from the LSR 114 as the starting point to reach theLSR 116 via the LSR 115.

In the portion where the transfer route of the LSP 308 is tunneled bythe tunneling LSP 307, the label assigned for the tunneling LSP 307 isstacked in front of the label assigned for the LSP 308, in the packettransferred through the LSP 308.

On the other hand, it is assumed that the 30 Mbits/sec. as the reservedbandwidth of the transit link is transferred in the LSP 308 is set ineach LSR. Even in the tunneling LSP 307, reservation of the bandwidth at30 Mbit/sec. is made for accommodating the LSP 308.

Attempt is made to establish the LSP from the LSR 112 to the LSR 118.Then, the bandwidth of the newly established LSP is assumed to be 20Sec/sec.

At first, LSR 112 derives the route to the LSR 118 using a topologyinformation collected by the OSPF. In the OSPF, concerning the area thatLSR 112 belongs to, connecting state of the links 210 to 215 may beseen. However, concerning the outside of the area that LSR 112 belongsto, it can be seen only accessibility. Therefore, as the result ofcalculation, LSR 112 should be only appreciated that the LSR 114 has tobe passed to reach the LSR 118.

The LSR 112 transmits the LSP set up request (label request message) 419to the LSR 114. In the LSP setup request 419, information indicatingthat the transit node is LSR 114 and the destination is LSR 118 andtraffic parameter as 20 Mbits/sec. as the bandwidth to be reserved.

The LSR 114 upon receipt of the LSP setup request 419 performs routingto the LSR 118. As a result of routing, it can be appreciated that LSR115 and the LSR 116 are to be passed in the backbone 4.

Here, check is performed whether or not the LSP that may have the routeto the egress LSR 118 in common with the newly established LSP ispresent. Namely, check is performed whether or not the LSP reaching thestep 118 via the LSR 115 and the LSR 116 is present or not. Here, suchLSP is not present.

Therefore, check is again performed whether the route at the terminalpoint of the tunneling LSP set in the LSR 114 can be a part of thetransit route of the LSP to be set. Here, check is performed whether ornot the tunneling LSP having the terminal point at the LSR 116 via theLSR 115, is present. Accordingly, the tunneling LSP 307 is selected ascandidate.

Next, check is performed whether or not the tunneling LSP 307 has theparameter of the reserved bandwidth. If the tunneling LSP 307 has thereserved bandwidth as parameter, the reserved bandwidth is modified to50 Sec/sec. as sum of 30 Mbits/sec. and 20 Mbits/sec. in the similarprocedure in the first embodiment of the present invention.

If modification of the reserved bandwidth of the tunneling LSP 307 issuccessful, setting of the LSP is performed through the sequence ofprocess that the LSP setup request 421 is transmitted from the LSR 114to the LSR 116, the LSP setup request 423 is transmitted from the LSR116 to the LSR 118, the LSP setup response 424 is transmitted from theLSP 118 to the LSR 116, the LSP set up response 422 is transmitted fromthe LSR 116 to the LSR 114, and the LSP setup response 420 istransmitted from the LSR 114 to the LSR 112.

Upon transmitting the LSP setup request 423 from the LSR 116 to the LSR118, the route to the LSR 118 is calculated by the OSPF to see that thenext hop is the LSR 118. Finally, the LSP 309 is set with taking the LSR112 as start point and the LSR 118 at terminal point via the LSR 114 andthe LSR 116.

Among the transfer route of the LSP 309, between the LSR 114 and the LSR116 as a portion to pass the backbone 4, the tunneling LSP 307 is used.In the backbone 4, for the packet transferred through the LSP 309, thelabel assigned for the tunnel LSP 307 is stacked in front of the labelassigned to the LSP 309.

On the other hand, 20 Mbits/sec. is set as reserved bandwidth in the LSP30. In the tunneling LSP 307, 50 Mbits/sec. as the reserved bandwidth asa sum of the 30 Mbits/sec. of the reserved bandwidth of the LSP 308 and20 Mbits/sec. of the reserved bandwidth of the LSP 309 is set.

In the backbone 4, the LSP 308 and the LSP 309 entering into the area 2is merged by the tunneling LSP 307, and is branched to the LSR 117 andthe LSR 118 as exiting to the area 3.

As set forth above, upon performing merge of the LSP, merge operation isperformed after modification of collateral parameter owned by theexisting LSP for accommodating the newly established LSP. By this, itbecomes possible to perform merge of the LSP having request bandwidth orthe like which has not been merged conventionally. Thus, greater numberof LSPs are merged to contribute for reduction of number of labels whichis inherent in expansion of scale of the network.

On the other hand, by accommodating a plurality of LSPs with collateralparameters in the preliminarily set tunneling LSP, merge is possibleonly in the portion of the tunneling LSP. For example, even when most ofthe LSPs pass the same portion in the network, merge cannot be performedunless the route up to the egress LSR is common. In contrast to this,according to the present invention, by setting the tunneling LSP for theportion where a plurality of LSPs pass the common route, merge becomespossible in the portion where the tunneling LSP is present.

As set forth above, with the communication connection merge systemaccording to the present invention, upon performing merge, collateralparameter, such as request bandwidth or the like may also be mergedtogether with LSP upon merging after modification of the collateralparameter of the existing LSP so that the newly established LSP may beaccommodated.

Also, in another communication connection merge system of the presentinvention, by accommodating a plurality of LSP switch collateralparameters in the preliminarily set tunneling LSP, merge in only portionof the tunneling LSP becomes possible. Therefore, it becomes possiblenot only to merge the LSPs together with the parameters, but also tobranch the LSPs at the mid-way even once merged.

While the present invention has been discussed in terms of the preferredembodiment, various modifications, omissions, additions and differentdesigns without departing from the principle of the invention should beobvious to those skilled in the art. Therefore, the present inventionshould be understood as including all possible embodiments,modifications, omissions, additions and so forth which can beimplemented without departing from the principle of the invention setforth in the appended claims.

1. A communication merge method, performed by a processor in aconnection-oriented network, which consolidates an existingcommunication connection having a first route to a first destinationnode with a second communication connection having a second route to asecond destination node, where said first and second destination nodesare different, comprising: determining, by the processor, whether atunneling communication connection is present from a third node to afourth node, where said third and fourth nodes are in both said firstroute and said second route; determining, by the processor, whethermodification of a parameter of said tunneling connection is possible, ifsaid tunneling communication connection is present; modifying, by theprocessor, the parameter of said tunneling communication connection toaccommodate a merger of said existing and second communicationconnections, if modification is possible; and merging, by the processor,said communication connections on said tunneling communicationconnection.
 2. The communication merge method of claim 1, where saidexisting communication connection is a tunneling communicationconnection.
 3. The communication merge method of claim 1, where saidmethod further comprises: creating a new tunneling communicationconnection from a fifth node to a sixth node, where said fifth and sixthnodes are in said first route and second route, if said tunnelingcommunication connection is not present.
 4. The communication mergemethod of claim 1, where said connection-oriented network includes amulti-protocol label switching network, said existing and secondcommunication connections include a label switched path, and said first,second, third, and fourth nodes include a label switching router.
 5. Thecommunication merge method of claim 1, where said connection-orientednetwork includes an asynchronous transfer mode network, said existingand second communication connections include a virtual channel, saidtunneling communication connection includes a virtual path, and saidfirst, second, third, and fourth nodes include an asynchronous transfermode switch.
 6. The communication merge method of claim 1, comprising:stacking a label assigned for the tunneling communication connection ina shim header.
 7. The communication merge method of claim 1, where saidparameter includes a bandwidth parameter.
 8. The communication mergemethod of claim 1, further comprising: determining, at least one othernode, if modification of the parameter is possible; and temporarilysetting, by the at least one other node, the modification of theparameter when modification of the parameter at the at least one othernode is possible.
 9. A node that consolidates communication connectionshaving different destination nodes in a connection-oriented network,comprising: a processor that: determines whether a tunnelingcommunication connection is present in a first route of an existingcommunication connection and in a second route of a second communicationconnection, determines whether modification of a parameter of saidtunneling communication connection is possible, modifies the parameterof said tunneling communication connection to accommodate merging saidsecond communication connection in said tunneling communicationconnection, if modification is possible, and merges said existingcommunication connection and said second communication connection onsaid tunneling communication connection.
 10. The node as set forth inclaim 9, where said existing communication connection includes atunneling communication connection.
 11. The node at set forth in claim9, where said processor creates a tunneling communication connectioncapable of accommodating said existing communication connection, wheresaid tunneling communication connection is in said first route and saidsecond route.
 12. The node as set forth in claim 9, where saidconnection-oriented network includes a multi-protocol label switchingnetwork, said existing and second communication connections include alabel switched path, and said node includes a label switching router.13. The node as set forth in claim 9, where said connection-orientednetwork includes an asynchronous transfer mode network, said existingand second communication connections include a virtual channel, saidtunneling communication connection includes a virtual path, and saidnode includes an asynchronous transfer mode switch.
 14. The node as setforth in claim 9, where said parameter includes a bandwidth parameter.15. The node as set forth in claim 9, further comprising at least oneother node, where the at least one other node: determines ifmodification of the parameter is possible, and temporarily sets themodification of the parameter when modification of the parameter at theat least one other node is possible.
 16. A method comprising:determining whether a tunneling communication connection is present inan existing communication connection including a first route to a firstdestination node and a second communication connection to be newly setincluding a second route to a second destination node, where said firstnode and said second node are different nodes, and wherein a pluralityof nodes are associated with the tunneling communication connection;sending a parameter modification request from one of the nodes to atleast one other node; receiving, from the at least one other node, aparameter modification response that indicates whether modification of aparameter is possible at the at least one other node; fixedly modifyingthe parameter of the tunneling communication connection whenmodification of the parameter is possible at the at least one othernode; and merging said communication connections on said tunnelingcommunication connection based on the fixedly modified parameter. 17.The method of claim 16, where the parameter includes a bandwidthparameter.
 18. The method of claim 16, where said existing and secondcommunication connections include a label switched path, and said firstand second nodes include a label switching router.
 19. The method ofclaim 16, where said existing and second communication connectionsinclude a virtual channel, said tunneling communication connectionincludes a virtual path, and said first and second nodes include anasynchronous transfer mode switch.
 20. The method of claim 16,comprising: creating a new tunneling communication connection from athird node to a fourth node, wherein said third and fourth nodes are insaid first route and second route, if said tunneling communicationconnection is not present.